Rudder area below the horizontal stabiliser is based upon a 1930s piece of RAE research, developed further in the 1950s by NASA called "Tail Damping Power Factor". NASA themselves revisited it in the 1970s and published a report saying that it was misleading and should not be used. Brunel University in the UK a few years ago also revisited it, concluded the same, and published similar papers in Aeronautical Journal.
The problem found with TDPF was using it against the aircraft "inertia yawing moment" in a simple equation. "Unshielded rudder volume" (area not blocked from the airstream by the horizontal stabilizer) is still very important to effective spin recovery. It doesn't take an aeronautical engineer to understand that having extra rudder in clear air would help slow a spinning aircraft.
Here's a link the NASA TDPF document:
http://naca.central.cranfield.ac.uk/...ca-tn-1045.pdf
67M Mk.II is a non-military 160hp variant. M200 and M260 are the models actually sold to the world's military forces.
From the Slingsby Owners' Club website:
he T67M-Mk2 variant was the first of the series used by the Royal Air Force for Elementary Flying Training.
The Canadian RAF flew the T67C.
I'm still trying to figure out all the T67 models. Could you guys look this over and see if you agree?
Specific question,
where is the T67M200 fuel tank(s) located? Firewall or wings?
T67 Firefly Models
T67A 1981 O
-235 4 cylinder 118hp engine, copy of RF-6B, made of wood, 2 blade fixed prop, fuel in firewall tank, single piece canopy, 10 built
T67B 1984 O-235 4 cylinder 118hp engine, made of glass reinforced plastic as are all models below, 2 blade fixed prop, fuel in firewall tank, single piece canopy, 6 built
T67M 1983 AEIO-320 fuel injected 4 cylinder 160hp engine, 2 blade constant speed prop, fuel in firewall tank, inverted flight systems, single piece canopy, 32 built (32 includes the T67M MKII)
T67M MKII 1985 with AEIO-320 fuel injected 4 cylinder 160hp engine, 2 blade constant speed prop, fuel in wing tanks, inverted flight systems, 2 piece canopy
T67C 1987 with O-320 4 cylinder 160hp engine, 2 blade constant speed prop, non-inverted systems, fuel in firewall tank, single piece canopy, 28 built. Some T67C's were built with two piece canopies and wing fuel tanks. The Canadian RAF flew the T67C3 with 2 piece canopies and wing fuel tanks.
T67M200 1987 with
AEIO-360-A1E fuel injected 4 cylinder 200hp engine, 3 blade constant speed prop, fuel tanks located ?, inverted flight systems, 26 built
T67M260 1993 with AEIO-540-D4A5 fuel injected 6 cylinder 260hp engine, 3 blade constant speed prop, fuel in wing tanks, inverted flight systems, 51 built
T67M260-T3A 1993 with IO-540-D4A5 fuel injected 6 cylinder 260hp engine, 3 blade constant speed prop, fuel in wings, inverted flight systems, air conditioning, all had "small" rudder, 114 built and sold to US Air Force. Four were destroyed in accidents, Edwards flight test kept one, the rest were scrapped.